The overall objective is insight into nervous integration at immediate levels, in terms of signals and processing. The approach is comparative. The material mainly the octovo lateralis and associated systems in lower vertebrates, especially fishes from hagfish to teleosts, but also some tetrapods and some invertebrates. The methods are electrophysiolgical, recording of units and populations. Five groups of questions are being asked. (1) Comparison of filtering and encoding properties of electro-acoustic, vestibular and lateral line receptors in diverse groups of fishes. (2) Comparison of reliability and slow fluctuations not caused by known input, among the same receptors and groups, and in their central relays. (3) Comparison of change of meaning of activity at successive central levels in these afferent systems. (4) Modes of mixing and weighting inputs and switching between modes, including plastic changes like compensation. (5) Comparison of field potentials of organized populations of cells, both ongoing (EEG) and evoked potentials, at different c.n.s. levels, in different modalities and major groups of vertebrates and invertebrates.